Process for inhibiting formation of intermetallic compounds in carbothermically produced metals

ABSTRACT

A process for inhibiting formation of intermetallic compounds in metal and metalloid containing alloys produced by carbothermic reduction of clay or ore, wherein molten alloy is removed from a reduction furnace, transferred to a holding pot, ladle or other suitable container, maintained at a temperature at least as high as the melting temperature of the lowest melting intermetallic compound, and then rapidly cooling the alloy, thereby minimizing the formation of intermetallic compounds. Cooling is preferably achieved by blowing the melt or by quenching.

United States Patent Valdo et a1.

*Oct. 7, 1975 PROCESS FOR lNl-llBlTlNG FORMATION OF INTERMETALLICCOMPOUNDS IN CARBOTHERMICALLY PRODUCED METALS lnventors: Alex R. Valdo,Elgin, 111.; Freeman M. Sanderford, Dalton, Ga.

Assignee: Ethyl Corporation, Richmond, Va.

Notice: The portion of the term of this patent subsequent to Oct. 26,1988, has been disclaimed.

Filed: Sept. 11, 1972 Appl. No.: 287,974

Related US. Application Data Continuation-impart of Ser. No. 164,952,-.luly 21, 1971, Pat. No. 3,704,117, which is a continuation-in-part ofSer. No. 744,307, July 12, 1968, Pat. No, 3,615,343.

US. Cl 75/68 A; 75/.5 B; 264/12; 264/13 Int. Cl. C2213 21/06 Field ofSearch 75/68 R, 68 A, 148, .5 B, 75/.5 C, .5 R, .5 A; 148/115 A; 264/12,13, 14

[56] References Cited UNITED STATES PATENTS 2,738,548 3/1956Kassel............. 264/14 2,967,351 1/1961 Roberts et a1 75/.5 83,325,279 6/1967 Lawrence et a1. 75/148 3,374,089 3/1968 Robinson, Jr.et al..., 75/68 R 3,615,343 10/1971 Valdo et a1 75/.5 B 3,704,11711/1972 Valdo et al. 75/.5 C

Primary Examiner-M. .l. Andrews Attorney, Agent, or Firm-Donald L.Johnson; John F. Sieberth; Paul H. Leonard [57] ABSTRACT 11 Claims, NoDrawings PROCESS FOR INHIBITING FORMATION OF INTERMETALLIC COMPOUNDS INCARBOTHERMICALLY PRODUCED METALS C ROSS-REFERENCES TO RELATEDAPPLICATIONS This application is a continuation-in-part of US.application Ser. No. 164,952, filed July 21, 1971, now U.S. Pat. No.3,704,117, which in turn is a continuation-in-part of US. applicationSer. No. 744,307, filed July 12, 1968, now US. Pat. No. 3,615,343.

This invention is directed toward a novel technique for purification ofalloys, and aluminum alloys in particular. Since many alloys containundesirable impurities, it is frequently necessary to remove theseimpurities or at least reduce the quantity thereof before beneficial usecan be made of the alloy. Consequently, there presently exists a needfor a simple and inexpensive method for purifying alloys by reducing thequantity of undesirable impurities, such as intermetallic compounds, inthese alloys.

This invention is particularly directed toward a process for purifyingalloys produced by carbothermic reduction of clay or ore. Aluminumalloys manufactured by the carbothermic reduction technique frequentlycontain, in addition to free aluminum, varying quantities of aluminum,silicon, iron and titanium in various intermetallic forms. Considerableheat is necessary to carbothermically reduce a natural ore or clay to ametal alloy. Furnace temperatures of about 2000C to about 2300C arenormally required to produce an aluminum-silicon alloy from analumina-silica ore. The present invention provides a means forinhibiting the formation of these intermetallic compounds utilizing theheat produced in the carbothermic reduction process.

Accordingly, it is an object of this invention to provide a process forreducing the content of undesirable intermetallic compounds in variousalloys produced by carbothermic reduction of clay by thermally causingthe compounds to dissociate.

Another object of the invention is the purification of suchcarbothermically produced alloys which can be utilized commerciallyafter removal of certain impurities.

In accordance with this invention, there is provided a process forreducing the content of one or more undesirable intermetallic compoundsin a carbothermically produced alloy by transferring molten alloydirectly from a carbothermic reduction furnace to a ladle or othersuitable holding container and maintaining the molten alloy at a highenough temperature for a sufficiently long time to inhibit the formationof the intermetallic compounds and then rapidly cooling the alloy tominimize formation of the intermetallic compounds. The heat retainedprevents formation of the intermetallic compound or compounds to theconstituent elements and the subsequent quenching retards formation ofthese undesirable compounds by effecting a rapid temperature dropthrough the formation temperature of the compound.

The invention is characterized by convenient flexibility in thatsubstantially any alloy containing one or more undesirable intermetalliccompounds can be purified provided the alloy is capable of undergoingperitectic decomposition. The term peritectic may be defined as anisothermal reversible reaction in which a molten liquid phase reactswith a solid phase to produce another solid phase on cooling. Thisinvention is directed toward the elimination of, or at least reductionin, the amount of certain intermetallic compounds present in this solidphase formed when the molten alloy is cooled. Thus, the term peritecticdecomposition" is used to denote the process of reducing the quantity ofcertain intermetallic compounds present in the alloy. This isaccomplished by transferring the molten alloy from the reduction furnaceto a holding container and maintaining the alloy at a temperature abovethe formation temperature of the intermetallics then rapidly quenchingthe alloy by blowing the melt, with ice water or in other suitablemanner, to minimize the formation of the undesirable intermetalliccompounds in the solid phase produced by cooling of the molten alloy. Inthis manner it has been found that a solid phase may be formed whichcontains innocuous amounts of the compound sought to be eliminated.

Substantially any alloy may be easily purified according to thetechniques of this invention, magnesium alloys, zinc alloys and the likebeing exemplary. Alloys containing aluminum are particularly well suitedto upgrading by the instant process. Aluminum alloys which are readilysusceptible to purification may have an alu minum content varying from afraction of a percent up to 99 percent and higher.

Aluminum alloys which are particularly susceptible to purification bythis process are those containing from about 40% to about aluminum byweight. The aluminum may be alloyed with substantially any element solong as one or more intermetallic compounds are present, the removal ofwhich is desired.

Exemplary of the metals and metalloids which may be present asintermetallics with aluminum in these alloys are iron, carbon, silver,boron calcium, cobalt, chromium, manganese, nickel, titanium, uranium,vanadium, zinc, copper and silicon. Two or more of these, and otherelements may be present in varying proportions with aluminum and mayeasily be removed from the alloy by the process of this invention. Forexample, common aluminum alloy-intermetallic constituents which readilyundergo peritectic decomposition and which are therefore susceptible ofbeing removed by application of the inventive process are FeAl MnAlCuMgAl TiAl FeSi Al and Al Ti Si Of the foregoing intermetalliccompounds which are frequently found to be undesirable constituents ofaluminum alloys, compounds containing at least 2 of the elements,aluminum, silicon, titanium, iron, copper, magnesium and manganese areparticularly significant because they are frequently found in thosealloys obtained by the carbothermic reduction of clay.

Common intermetallic compounds contained in carbothermically producedaluminum alloys are FeSi- A1, and TiAl It will be recognized that manyother combinations are frequently found. It has been found that byapplication of this invention such undesirable intermetallic compoundsmay be thermally decomposed, thereby enriching the aluminum content ofthe base aluminum alloy.

As previously noted, a basic feature of the invention is retainingsufficient heat in the impure alloy to maintain its temperature at leastabove the melting point of the intermetallic compound which is to beinhibited from forming in the alloy. Suitable temperatures which may beutilized in the invention are dependent upon the melting temperature ofthe intermetallic compound which is to be reduced in any given alloy. Ingeneral, however, temperatures in the range of from about 300C to aboutl400C are high enough to melt intermetallic compounds which aresusceptible to peritectic decomposition. For example, if decompositionof the intermetallic FeSi Al is to be accomplished in an aluminum alloycontaining by weight about 68% aluminum, 27% silicon, 3% iron and 2%titanium, the alloy should be maintained at a temperature of at least870C (which is the melting temperature of this intermetallic compound)before rapid cooling is effected. Similarly, if it is desirable toremove TiAl from an alloy having the same or a similar composition, atemperature of at least 1340C should be maintained before quenching thealloy.

In order to insure that substantially all of the intermetallic compoundis melted, it is preferable to keep sufficient heat in the alloy tomaintain the alloy at a temperature somewhat above the melting point ofthe intermetallic, sufficiently above the melting point to yield a fluidmelt. ln blowing from the melt, the alloy containing the intermetallicsmust be maintained at a temperature sufficiently high to keep the metalmolten. The metal must be in a fluid state before it can be blown.

The length of time at which the alloy should remain at the intermetallicmelting point is not critical, but it should be long enough to insurethat all of the undesirable intermetallic compound or compounds aremaintained in a molten state.

After the molten alloy is tapped from the furnace and transferred to aholding pot or ladle, it should be maintained at an appropriatetemperature to prevent formation of the intermetallic compounds. Whensolidification of the alloy is desirable, it should be rapidly cooled inorder to prevent the formation of these compounds, as heretofore noted.Rapid cooling is accomplished by blowing the melt, or quenching, theprocedures for which are described hereinafter.

The equipment satisfactory for carrying out the blowing of a moltenalloy consists of a graphite crucible equipped with an induction heatingcoil wrapped around the outside of the crucible so that the charge canbe heated to the desired temperature by induction. The crucible has ahole in the bottom thereof to which is attached a graphite tube. Agraphite rod is placed in the crucible to close the graphite tube andcontain the molten alloy in the crucible until the blowing operation isconducted. Twenty-four air jets are mounted concentrically around thegraphite tube in the shape of a cone with the apex of the cone pointeddownward so that the stream of air which is discharged from the jets isdirected to the discharge end of the graphite tube. This assembly ismounted on a refractory slab which in turn mounted on a metal cylinder.The graphite tube and air jets extend through a hold in the refractorycover so that the blown powder is retained by and collected in the metalcylinder. The metal cylinder is equipped with openings at its top toserve as vents for the air discharged through the air jets.

The alloy to be treated is charged in molten form to the graphitecrucible. The crucible is heated by induction to the desired temperatureto maintain a homogeneous, fluid melt of alloy. The induction fieldinduces a gentle rolling action within the melt which maintainshomogenization.

After a desired time, a valve is opened to admit air to the jets mountedaround the bottom of the graphite tube. The graphite rod is then removedfrom the crucible, and the molten alloy flows through the graphite tubeand is atomized by the air from the jets. The atomized alloy fallsdownward in the metal cylinder, cools and solidifies and is collected inthe bottom of the cylinder. If the metal cylinder is tall enough, thealloy will be cooled sufficiently by the flow of air. If it is notpractical to use a tall cylinder, a pool of water can be placed in thebottom of the metal cylinder to effect final cooling and solidification.

The particle size of the blown power can be con trolled by varying theair pressure applied to the air jets and/or the diameter of the tubethrough which the molten alloy is discharged from the crucible. Ingeneral, the higher the air pressure, the smaller the particle size ofthe product alloy; the smaller the tube diameter, the smaller theparticle size. However, the tube diameter cannot be so small that themolten alloy cools and solidifies in the tube. in general, the finer theparticle size the more rapid is the cooling of the molten alloy and theless is the likelihood of undesirable intermetallics in the finalproduct.

This apparatus has been used by others to prepare pure metal powders andalloys. For example, nickel powder has been prepared by personnel in theCanadian Department of Mines using an apparatus and melt blowingprocedure similar to the foregoing.

Variations of the above apparatus and procedure can be employed withequal effectiveness. Hence, instead of having the air jets impinging onthe stream of molten metal to atomize the molten metal, the air can beintro duced into the tube above its discharge end and the alloy forcedthrough a nozzle attached to the end of the tube to atomize the moltenmetal. Gases other than air such as argon and nitrogen may be usedprovided they do not react with and contaminate the alloy to any greatextent. A stream of water may be used in place of air, and the use ofargon instead of air is especially suitable when it is desired toproduce an alloy powder having a minimum oxygen content. Materials ofconstruction may be used other than graphite, the main requirement beingthat they are compatible with the molten alloy.

Generally, a smaller residue of the undesirable intermetallic compoundhas been found in the alloy subjected to melt blowing as compared to analloy of the same composition which has been subjected to otherquenching techniques.

Another method for rapidly cooling the molten alloy is the use of an icewater quench to lower the temperature of the molten alloy as rapidly aspossible. Of course, it will be recognized by those skilled in the artthat many other quenching media and techniques may be utilizedsuccessfully in the cooling phase of this invention. In general, it ispreferably to quench the alloy at a rate of from about to about 400 persecond, and most preferably, about 200 per second.

it has been found that the product alloy, that is, the alloy which hasbeen purified by the technique of this invention, may be bestcommercially utilized in small particles. Of course, size reduction ofthe purified alloy' may be undertaken after purification by conventionaltechniques such as crushing, grinding, and other methods well known tothose skilled in the art. However, size reduction may be easily effectedin the course of this process by sieving the molten alloy after heatingit to the appropriate temperature. Thus, the molten alloy may be pouredthrough a screen having a mesh size proportional to the size of thefinished alloy particle desired, and when it is desired to utilize aliquid quench for cooling purposes, the molten alloy may be pouredthrough a screen or similar size reducing apparatus directly into thequenching medium.

Accordingly, a preferred embodiment of the invention is characterized byutilizing a molten alloy prepared by carbothermic reduction, containingaluminum, silicon, iron and titanium, wherein the intermetalliccompounds usually formed are composed of aluminum, silicon and iron andaluminum and titanium, respectively, maintaining a temperature withinthe range of from about 300C to about l400C and then rapidly cooling themolten alloy by rapidly blowing the melt. In a more preferredembodiment, the alloy contains by weight about 68% aluminum, 27%silicon, 3% iron and 2% titanium, the usually formed intermetalliccompounds are Fesi Al the molten alloy is maintained in an inertatmosphere at a temperature of about l340C or higher keeping the meltfluid, after which the alloy is cooled by rapidly blowing the melt,quenching or the like.

As heretofore mentioned, it is desirable to inhibit formation of certainundesirable intermetallic compounds normally present in alloys withoutsimultaneously producing additional undesirable compounds. Consequently,the inventive process defines a technique for inhibiting the formationof intermetallic compounds in a variety of metal andmetalloid-containing alloys produced by carbothermic reductiontransferring the molten alloy to a suitable container and maintainingthe alloy at a temperature at least as high as the melting temperatureof the intermetallic compound to be prevented from forming but below themelting temperature of at least one of the metals or metalloids in thealloy, the yield of which it is desired to increase. Once solidificationof the alloy is desired, the alloy should be rapidly cooled by blowingthe melt, quenching or the like.

This technique prevents the formation of undesirable intermetallics inthe alloy. Subsequent rapid cooling of the alloy substantially preservesthe elemental components and inhibits formation of the undesirableintermetallics and minimizes the formation of other undesirablecompounds containing the metal or metalloid. In this aspect of theinvention a preferred alloy is composed of aluminum, silicon, iron andtitanium.

In one embodiment of the invention where the alloy contains themetalloid, silicon, it is desirable to maintain the alloy at atemperature above the melting point of the intermetallic compound orcompounds to be decomposed but below the melting temperature of thesilicon, and then rapidly cool the alloy in order to increase the yieldof silicon in the cooled alloy. As above noted, this technique inhibitsformation of intermetallic compounds in the alloy and also substantiallyreduces the amount of silicon-containing compound in the quenched alloy.In this manner, the quantity of elemental silicon or other element in agiven alloy may be increased. As in previous embodiments of theinvention, the temperature may generally be maintained within the rangeof from about 300C to about 1400C and should be maintained sufficientlyhigh to maintain the melt in molten condition. Further, the coolingstage of the process is effected by rapidly blowing the melt, quenchingor the like.

In a most preferred embodiment of the invention the alloy treatedcontains by weight about 68% aluminum, 27% silicon, 3% iron and 2%titanium and the interme tallic compounds tending to be formed are FeSiAl Al Ti Si and TiAl Further, the molten alloy is maintained at atemperature of about 1340C (which is below the melting point of silicon)in an inert atmosphere such as nitrogen or argon. The cooling phase iseffected by rapidly blowing the melt.

This invention and the various embodiments thereof may be furtherunderstood by the following illustrative examples. In all cases thealloy used was a synthetic alloy which simulated an alloy produced by acarbothermic reduction process.

EXAMPLE Approximately 500 grams of an alloy containing by weight 68percent aluminum, 27 percent silicon, 3 percent iron and 2 percenttitanium and having a Fesi Al. content of about 20 weight percent wereheated to l,000C in a large crucible and held at this temperature for 30minutes. The molten metal was then rapidly quenched in ice water bypouring the alloy directly into a water-ice mixture having a temperatureof 2C. After the quenching operation, the alloy was analyzed and foundto contain 5.5 percent by weight of the FeSi Al intermetallic compound.

EXAMPLE ll Three hundred forty-five grams of an alloy having the samecomposition as that used in Example ll were heated in a crucible to atemperature of 1,000C where it was held for 15 minutes and vigorouslystirred. The molten alloy was then poured through a stainless steelscreen into ice water, the temperature of which was 2C. Small particlesof alloy were observed to form in the ice water. The analysis of Fesi Ahpresent in the alloy after quenching was found to be 9 percent byweight.

EXAMPLE lll Ten grams of silicon alloy containing percent by weight ofsilicon, 5 percent by weight of aluminum, 19 percent by weight of FeSiAl and 1 percent by weight of TiAl were heated in a crucible to l200Cand held at that temperature for 15 minutes. The alloy was then allowedto cool in air. The cooled alloy was subjected to X-ray analysis whichshowed on a weight basis, 82.4 percent silicon, 1.6 percent aluminum,7.4 percent FeSi Al and the presence of two unknown intermetalliccompounds.

EXAMPLE 1V Twenty-five grams of an alloy containing by weight 73 percentsilicon, 5 percent aluminum, 22 percent FeSi AI, and a trace of TiAlwere heated in an argon atmosphere to l,000C, held for 15 minutes andsubsequently quenched in ice water. Upon X-ray analysis, the FeSi Al.content was found to be 2.2 percent by weight and there appeared to beno trace of TiAl left in the alloy.

EXAMPLE V Three 10 gram samples of aluminum alloy containing by weight27.4 percent aluminum, 50.2 percent silicon,

8 percent iron (Fesi Al, was present in an amount equal to 19 percent byweight) and 0.4 percent titanium were heated to temperatures of 800C,900C and lOC, respectively. The alloy samples were held at theserespective temperatures for minutes and were then rapidly quenched inice water. X-ray analysis of the three samples showed the Fesi Al,content of the samples by weight as follows: 800C 14.9 percent; 900C14.9 percent; lO00C 1.9 percent.

Example V clearly illustrates that for best results the alloy to bepurified should be heated to a temperature significantly above themelting point of the intermetallic compound to be decomposed. Themelting point of FeSi,Al as previously noted, is about 870C, and theresults of Example V show that much more FeSi,Al impurity is removed byquenching from a temperature of lO00C (well above 870C) than from thetemperatures below and even slightly above the intermetallic compoundmelting point.

From an analysis of the preceding examples and embodiments it isapparent that the invention provides an easy and economical method fordecomposing a quantity of undesirable intermetallic compound invirtually any alloy capable of undergoing peritectic decomposition.Operation procedures are simple and necessary equipment is not expensiveand is readily available. Accordingly, the invention contributes to theart of alloy purification.

EXAMPLE VI A sample of Al-Si-Fe-Ti alloy, having the composition byweight 62% Al, 33% Si, 2% Fe, 3% Ti, was melted at 1250C to give ahomogeneous liquid which was then atomized by allowing it to flowthrough a /4 inch tube and directing a stream of water at 200 psi ontothe molten metal stream. The resultant powder was 95% mesh and 85% I00mesh. X-ray diffraction analysis of the resultant powder gave adiffraction pattern which contained no peaks assignable to the FeSi,Alintermetallic and only two small peaks which might be assignable to anAl-Si-Ti intermetallic. Hence, the product contained at most traceamounts of the Al- Si-Ti intermetallic. On the other hand, a comparisonsample having essentially the same composition but which was cooled andcrystallized slowly gave an X-ray pattern which showed the presence ofsmall, but detectable amounts of FeSi Al and about 6% of the Al- Si-Tiintermetallic.

EXAMPLE VII An aluminum-silicon-iron-titanium alloy composition wasprepared by placing weighed amounts of the individual metals in agraphite crucible and heating the crucible in an induction coil to l400Cto form a fluid homogeneous melt which was held at I400C for IS minutes.The molten alloy was then forced through a discharge tube under argonpressure and atomized by blowing the metal through a nozzle connected tothe end of the discharge tube. The blown alloy was ana lyzed by X-rayfluorescence (XRF). X-ray diffraction (XRD) analysis of the powdershowed it to contain little or no intermetallics as set forth in Table Ihereinafter.

Two other Al-Si-Fe-Ti alloy compositions were prepared by meltingweighed amounts of the individual metals in a graphite crucible.However, these samples were not blown from the melt. Instead, thecrucible and molten alloy were removed from the furnace and allowed tocool to room temperature. The solid alloy samples were removed from thecrucibles, crushed and ground. X-ray fluorescence (XRF) and X-raydiffraction (XRD) analyses of these samples are also set forth in TableI.

TABLE Alloy Compositions it can be clearly seen that both cast andground samples (2A and 28) contained more intermetallics than did thesample (1) blown from the melt.

EXAMPLE Vlll An alloy composition was prepared and blown according tothe procedure of Example ll. The composition of the resultant powder wasdetermined by X-ray fluorescence to be 56.0% Al, 32.7% Si, 3.1% Fe and2.8% Ti. X-ray diffraction analysis detected 2% FeSi- ,Al. and 5%AlgTigsig; no Fe Ti was detected.

For comparison, a second alloy sample was prepared, but was cooled,crushed and ground (instead of being blown). its composition wasdetermined by X-ray fluorescence to be 55.2% Al, 28.5% Si, 3.4% Fe and2.8% Ti. It was found to contain by X-ray diffraction 3% F eSi,Al,, 7%Al Ti si and about 1% Fe,Ti.

Again, it has been clearly demonstrated that substantially lessintermetallics are found when the alloy has been rapidly cooled byblowing the melt.

From an analysis of the preceding examples and embodiments it isapparent that the invention provides an easy and economical method forinhibiting the formation of undesirable intermetallic compound invirtually any carbothermically produced alloy capable of undergoingperitectic decomposition. Operating procedures are simple and necessaryequipment is inexpensive and is readily available. Accordingly, theinvention contributes to the art of alloy purification.

The foregoing disclosure and description of the invention isillustrative and explanatory thereof and various changes may be madewithin the scope of the appended claims without departing from thespirit of the invention.

What is claimed is:

1. In a process comprising carbothermically reducing an ore to form amolten alloy, the improvement in combination therewith for inhibitingthe formation of intermetallic compounds in metal andmetalloid-containing alloys produced by the carbothermic reduction ofthe ore and capable of undergoing peritectic decomposition, comprisingthe steps of transferring the molten carbothermically produced alloyfrom a carbothermic reduction furnace to a suitable container,maintaining the transferred alloy in the container at a temperature atleast as high as the melting temperature of any undesirableintermetallic compound but below the melting temperature of at least oneof the metals or metalloids in the alloy, the yield of which it isdesired to increase, and then rapidly cooling the alloy, therebyminimizing the formation of an undesirable intermetallic compound.

2. The process of claim 1, wherein the molten alloy is an aluminumalloy.

3. The process of claim 1, wherein said molten alloy contains aluminum,silicon, iron and titanium.

4. The process of claim 1, wherein at least one of the metals issilicon.

5. The process of claim 1, wherein said molten alloy is maintained at atemperature within the range of from about 300C to about 1400C andsufficiently high to maintain the alloy in a molten state.

6. The process of claim 1, wherein said rapid cooling is effected byrapidly contacting the alloy with a quenching medium.

7. The process of claim 1, wherein said rapid cooling is effected byblowing the melt.

8. The process of claim 1, wherein the molten alloy is sieved afterbeing transferred from the carbothermic reduction furnace.

9. The process of claim I, wherein (a) the molten alloy contains byweight about 68 percent aluminum, 27 percent silicon, 3 percent iron and2 percent titanium', (b) the molten alloy is maintained in an inertatmosphere at a temperature of about l340; and (c) said subsequent rapidcooling is effected by rapidly contacting the alloy with ice water.

10. The process of claim 9, wherein the alloy is sieved before beingcontacted with said ice water.

11. The process of claim 9, wherein said rapid cooling is effected byrapidly blowing the melt.

i l i i UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO.1 3,910,787

DATED 1 October 7, 1975 rrrvrzrrrords) I A. R. Valdo and F. M. Sander Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 3 lines 56 and 57,"which in turn mounted" should read which inturn is mounted Column 4, line 13, "power" should read powder Column 4,line 58, preferably" should read preferable Column 5, line 21, "FeSi Alshould read FeSi Al and TiAl3 Column 6, line 33, "Example II" shouldread Example I Signed and Scaled this sixth D y 0f January 1976 {SEAL}Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting ()jfr'cer (ummr'ssium'r 0]Parenlx and Trademarks

1. IN A PROCESS COMPRISING CARBOTHERMICALLY REDUCING AN ORE TO FORM AMOLTEN ALLOY, THE IMPROVEMENT IN COMBINATION THEREWITH FOR INHIBITINGTHE FORMATION OF INTERMETALLIC COMPOUNDS IN METAL ANDMETALLOID-CONTAINING ALLOYS PREDUCED BY THE CARBOTHERMIC REDUCTION OFTHE ORE AND CAPABLE OF UNDERGOING PERITECTIC DECOMPOSITION, COMPRISINGTHE STEPS OF TRANSFERRING TE MOLTEN CARBOTHERMICALLY PRODUCED ALLOY FROMA CARBOTERMIC REDUCTION FURNACE TO A SUITABLE CONTAINER, MAINTAINING THETRANSFERRED ALLOY IN THE CONTAINER AT A TEMPERATURE AT LEAST AS HIGH ASTHE MELTING TEMPERATURE OF ANY UNDESIRABLE INTERMETALLIC COMPOUND BUTBELOW THE MELTING TEMPERATURE OF AT LEAST ONE OF THE METALS ORMETALLOIDS IN THE ALLOY, THE YIELD OF WHICH IT IS DESIRED TO INCREASEAND THEN RAPIDLY COOLING THE ALLOY, THEREBY MINIMIZING THE FORMATION OFAN UNDESIRABLE INTERMETALLIC COMPOUND.
 2. The process of claim 1,wherein the molten alloy is an aluminum alloy.
 3. The process of claim1, wherein said molten alloy contains aluminum, silicon, iron andtitanium.
 4. The process of claim 1, wherein at least one of the metalsis silicon.
 5. The process of claim 1, wherein said molten alloy ismaintained at a temperature within the range of from about 300*C toabout 1400*C and sufficiently high to maintain the alloy in a moltenstate.
 6. The process of claim 1, wherein said rapid cooling is effectedby rapidly contacting the alloy with a quenching medium.
 7. The processof claim 1, wherein said rapid cooling is effected by blowing the melt.8. The process of claim 1, wherein the molten alloy is sieved afterbeing transferred from the carbothermic reduction furnace.
 9. Theprocess of claim 1, wherein (a) the molten alloy contains by weightabout 68 percent aluminum, 27 percent silicon, 3 percent iron and 2percent titanium; (b) the molten alloy is maintained in an inertatmosphere at a temperature of about 1340*; and (c) said subsequentrapid cooling is effected by rapidly contacting the alloy with icewater.
 10. The process of claim 9, wherein the alloy is sieved beforebeing contacted with said ice water.
 11. The process of claim 9, whereinsaid rapid cooling is effected by rapidly blowing the melt.